Portable cutting device

ABSTRACT

A portable cutting device includes a support structure provided with straps to permit mounting of the support structure on the back of a user, and the supporting structure also has a pump, reservoir and engine mounted thereon. An elongate hollow handle has a mounting plate at one end thereof which is connected to a cutting blade, and an operating valve is mounted on the other end of the handle. The cylinder and piston unit is connected to the blade and mounting plate, and the piston is provided with a valve therein which is operable to facilitate retraction of the piston upon release of the operating valve handle.

United States Patent Walsh PORTABLE CUTTING DEVICE [76] Inventor: Harold L. Walsh, 802 N. Park Ave.,

Park Rapids, Minn. 56470 [22] Filed: Mar. 23, 1973 [21] Appl. No.: 344,254

[52] US. Cl. 144/34 E, 30/228, 91/401 [51] Int. Cl A01g 23/08 [58] Field of Search 144/34 R, 34 E; 30/228; 91/401, 224; 92/181 [56] References Cited UNITED STATES PATENTS [451 Sept. 10, 1974 Primary Examiner-Donald R. Schran Attorney, Agent, or Firm-Williamson, Bains & Moore [5 7] ABSTRACT A portable cutting device includes a support structure provided with straps to permit mounting of the support structure on the back of a user, and the supporting structure also has a pump, reservoir and engine mounted thereon. An elongate hollow handle has a mounting plate at one end thereof which is connected to a cutting blade, and an operating valve is mounted on the other end of the handle. The cylinder and piston unit is connected to the blade and mounting plate, and the piston is provided with a valve therein which is operable to facilitate retraction of the piston upon release of the operating valve handle.

3 Claims, 6 Drawing Figures PAIENTEI] SEP 1 01924 814m 2 or 2 l PORTABLE CUTTING DEVICE SUMMARY OF THE INVENTION weight backpack mounting the various components of the hydraulic system thereon. The piston of the .piston and cylinder unit is provided with a valve which is operable at the end of the extension stroke of the piston to intercommunicate opposite sides of the piston and thereby facilitate retraction of the piston when a user releases the control valve for the device.

A more specific object of the invention is to provide a novel control valve which cooperates with a unique piston and cylinder unit to cause closing of the cutting unit when the operating handle of the control valve is depressed, and permitting the shears or cutting device to be readily opened upon release of the operating handle of the control valve, thereby obviating the necessity of springs for the piston and cylinder unit.

These and other objects and advantages of this invention will more fully appear from the following description made in connection with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout the several views.

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWING FIG. 1 is a perspective view of the portable cutting device illustrating one manner of use thereof,

FIG. 2 is a perspective view of the control valve,

FIG. 3 is a cross-sectional view taken approximately along line 3-3 of FIG. 2 and looking in the direction of the arrows and illustrating the control valve with the valve member in one position of use,

FIG. 4 is a cross-sectional view of the control valve similar to FIG. 3 but illustrating the valve member in another position of use,

FIG. 5 is a cross-sectional view taken approximately along line 5-5 of FIG. 4 and looking in the direction of the arrows, and

FIG. 6 is a fragmentary cross-sectional view of the piston and cylinder unit which is used to operate the cutting blade of the cutting device.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings and more specifically to FIG. 1, it will be seen that one embodiment of the novel cutting device, designated generally by the reference numeral 10 is thereshown. The portable cutting device 10 includes an elongate generally tubular handle 11 which is provided intermediate its ends with a hand grip element or arm 12. The lower or outer end of the handle 11 is rigidly affixed to a substantially flat mounting plate 13, the latter having a substantially straight, normally vertically oriented, blade engaging surface 14.

A substantially flat blade 15 is pivotally connected to the mounting plate 13 by means of pivot 16. The blade has a V-shaped extension 17 affixed thereto and the blade is also provided with a cutting edge which cooperates with the blade engaging surface of the mounting plate to facilitate cutting small trees and the like.

Means are provided for shifting the blade towards and away from the blade engaging surface of the mounting plate and this means includes a hydraulic piston and cylinder unit 18. The unit includes an elongate cylinder 19 which has one end thereof pivotally connected to the mounting plate 13. The cylinder 19 is provided with a piston 20 which is movable therein and the piston has a piston rod 21 secured thereto and projecting exteriorly of the cylinder The outer end of the piston rod 21 is pivotally connected to the apex of the V-shaped extension 17 so that when the piston rod 21 is extended, the blade will be closed and moved into engaging relation with the blade engaging surface 14 of the mounting plate 13. However, when the piston rod 21 is retracted, the blade will be shifted away from the mounting plate and into the open position. The interrelation and construction of the handle 11, mounting plate 13, blade 15, and piston and cylinder unit 18 is similar in construction and operation to that shown in US. Pat. No. 3,495,637.

Referring now to FIG. 6, it will be seen that the piston 20 has an annular groove 22 therein intermediate the opposed faces thereof while one face of the piston has a pair of small circular recesses 23 therein. The other face of the piston has a large circular recess 24 therein, and it will be noted that an axially extending bore 25 extends through the piston and intercommunicates one of the small recesses 23 with the large recess 24. A valve stem 27 is positioned in the bore 25 and is axially shiftable therein opposite end' portions of the valve stem having valve heads or closures 28 affixed thereto.

The valve stem 25 projects beyond one of the valve heads 28 to define an extension 29, this extension projecting beyond the face of the piston when the other valve head is positioned against the surface defined by the recess 23. A plurality of axially extending passages 26 arranged in circular extend through the piston 20 and intercommunicate the recess 23 with the large recess 24. The circular pattern formed by the passages 26 is slightly smaller than the flat face of the valve heads 28 whereby these passages will be alternately closed by one or the other of the valve heads when one of the valve heads is positioned in engaging relation with one of the surfaces of the piston through which the passages extend. The cylinder 19 has suitable fittings at opposite end portions thereof and these fittings are connected respectively to conduits 30 and 31. Thus hydraulic fluid under pressure may be selectively supplied through either conduit 30 and 31 to permit power shifting of the piston in the cylinder. Thus the piston and cylinder unit 18 is a double acting unit.

The conduits 30 and 31 extend completely through the interior of the elongate hollow handle 11 and are connected into communicating relation to a novel control valve mechanism 32. The valve mechanism 32 includes a housing 33 having a threaded recess 34 and a threaded recess 35 therein. The threaded recess 34 is connected to the fitting secured to one end of the conduit 30 and the threaded recess 35 is connected to the fitting of the conduit 31.

The threaded recess 34 communicates with an elongate substantially straight passage 36 which as shown extends completely through the housing 33 from one end thereof to the other. An enlarged threaded recess 37 is formed in the other end of the housing 33 and communicates with the passage 36.

The threaded recess 35 communicates with a passage 39 which in turn is connected in communicating relation to a transverse passage 40 which is connected in communicating relation to passage 36. The passage 40 is formed by drilling from one side of the housing and this passage is closed by a suitable plug as best seen in FIGS. 3 and 4. V p

A second transverse passage 41 is formed in the housing 33 and its innermost end is reduced to define a relief port 42 which intercommunicates with the passage 36. A ball type check valve 43 is provided for the port 42 and is urged into closing relation by helical spring 44. A longitudinal passage 45 communicates with the passage 41 and is connected in communicating relation with respect to a threaded recess 46. The threaded recess 37 is connected in communicating relation to a conduit 47 by means of the fitting carried by the conduit, and the threaded recess 46is connected to the fitting carried by one end of an elongate conduit 48.

Referring now to FIGS, 3, 4 and 5, it will be seen that passage 45 is interconnected by an oblique passage 49 to an outlet 50 which communicates with a relatively large bore 51 that extends. completely through the valve housing 33 from the upper surface thereof to the lower surface thereof. The bore 51 accommodates an elongate generally cylindrically shaped valve member 52 which is shiftable in the bore and which projects outwardly from opposite ends thereof. The valve member 52 has a longitudinal passage 53 therein which communicates at one of its ends with an opening 54 and communicates at its other end with an opening 55. The valve member 52 also has an intermediate opening 56 therein which intercornmunicates the longitudional passage 53 thereof with the opening 50 in the bore 51. Thus it will be seen that the opening 56 is constantly intercommunicated with the passage 49 and therefore the passage 45.

One end of the valve member 52 is internally threaded for receiving the threaded end of an elongate bolt 57, a washer or coller 58 being provided for anchoring one end of the valve member. A helical spring 59 is positioned around one end portion of the valve member 52 and has one end thereof engaging the washer 58 and has its other end engaging the adjacent surface of the housing. With this arrangement, axial movement of the valve member 52 in one direction is yieldably resisted by the spring 59.

The other end portion of the valve member 52 is pivotally connected by a pivot 60 to one end of an elongate operating lever or handle 61. The operating lever 61 is provided intermediate its ends with a pair of attachment ears 62 which are pivotally connected by a pivot 63 to a fulcrum or attachment element 64. It will be noted that the fulcrum or attachment element is secured to the housing 33 and projects outwardly therefrom. It will also be noted that when a user depresses the operating lever 61, the valve member 52 is shifted axially relative to the housing 33 against the bias of the spring 59. When the operating lever 61 is released by a user, the spring 59 will quickly return the valve member 52 to its original position. the portable cutting device is provided with suitable power means for the hydraulic system, and the components of this system are mounted on a substantially flat lightweight mounting structure 65 which may be constructed of a suitable rigid material such as metal, plastic or the like. This mounting structure 65 is provided with suitable shoulder straps 67 and waist straps 68 which are releasably connected together in a suitable fashion adjacent the frontal thoracic area of a user so that the mounting structure is mounted against the users back.

The mounting structure 65 has a small internal combustion engine 69 mounted thereon, the engine being provided with a suitable starter 70 and a fuel tank 71. A reservoir or tank structure 72 is also mounted on the mounting structure and this reservoir is adapted to contain a predetermined amount of hydraulic fluid. The reservoir 72 is interconnected to a pump 74 by means of a conduit 73 as best seen in FIG. 1. It will be noted that the conduit 47 is connected in communicating relation to the pump 74 while the conduit 48 is connected in communicating relation with respect to the reservoir 72. A suitable filter 75 is interposed in flow controlling relation with respect to conduit 48. It is also pointed out that the conduits 47 and 48 are provided with suitable quick coupling mechanisms intermediate their ends to permit the mounting structure and the various components mounted thereon to be disconnected from the handle 11. With the present arrangement, the entire cutting device may be conveniently carried and operated by a user in cutting and harvesting small trees as well as effectively pruning trees, shrubs and the like.

During use of the portable cutting device, the mounting structure and its various components will be mounted on a back of a user and the various sections of the conduits 47 and 48 will be interconnected together. These disconnect quick couplings mechanisms which interconnect these portions of the conduits have suitable check valves in them and are of well known construction. When the operating handle 61 is in the released condition, the valve member 52 will assume the position illustrated in FIG. 3. When in this position, it will be noted that the passage 36 is obstructed by the valve member while the passage 39 is intercommunicated by means of the passage 40 with the passage 36. This condition is possible since the valve member 52 has a reduced annular portion 76 and a reduced annular portion 77 formed intermediate its ends. When in the released condition, the reduced annular portion 77 registers with the passage 39 while the passage 36 is obstructed by the valve member and hydraulic fluid cannot flow into the conduit 30. Therefore hydraulic fluid will flow through the conduit 37 into the passage 36 through the passage 40 and will exit through passage 39 into the conduit 31. When this occurs the piston 20 will be in the retracted position as illustrated in FIGS. 1 and 2. Excess pressure produced in the passage 36 between the valve member 52 and the conduit 47 may be relieved through the relief port 42 if the pressure exceeds a predetermined magnitude. The hydraulic fluid will then be returned through passage 45 into conduit 48 and back into the reservoir 72. It will also be noted that hydraulic fluid flowing through the conduit 30 from the cylinder 19 will pass through the passage 36 to the opening 54 and into the passage 50. The opening 55 of the valve member is constructed so the hydraulic fluid will flow outwardly through the opening 56 through the oblique passage 49 and thereafter out passage 45 into the conduit 48.

When the operating lever 61 is depressed, the valve member 52 will be moved axially against the bias of the spring 59. Thus the valve member will assume the position illustrated in FIG. 4 so that the reduced portion 76 of the valve member is positioned in registering relation with respect to the passage 36. The hydraulic fluid will flow directly through the passage 36 from the conduit 47 and outwardly through the conduit 30 by flowing around the annular passage defined by the reduced portion 76. The passage 39 will be obstructed by the valve member 52 although the opening 55 will be posi tioned in communicating relation with the passage 39. As the hydraulic fluid flows through conduit 30 into the cylinder 19, the valve stem 27 will be shifted axially so that one of the valve heads will be positioned against the passages 26 to obstruct the same. The piston 20 will be shifted axially in the cylinder to shift the blade to its closed position and thus effect the cutting of a tree as illustrated in FIG. 1. Hydraulic fluid which is evacuated from the cylinder will flow through conduit 31 into the passage 39 and thereafter through opening 55. The fluid will flow through the passage 53 in the valve member 52 and will exit through the opening 56 therein and then flow through the oblique passage 49 into the passage 45 where it will exit through the conduit 48.

When the operating lever 61 is again released, the valve member 52 will be returned to its original position by the coaction of the spring 59 therewith. The passage 36 will again be obstructed with respect to the pressure source while the passage 39 will be intercommunicated therewith. Thus hydraulic fluid will flow outwardly through the passage 39 into the conduit 31 to retract the piston. The hydraulic fluid will return to the conduit 30 into the passage 36 and through the opening 54 into the passage 50. The hydraulic fluid will exit through the opening 56 into the oblique passage 49 and thereafter flow outwardly through the passage 45 into the conduit 48.

As the piston approaches the end of the its travel in the retracted direction, the extension 29 of the valve stem will engage the end wall of the piston and will shift the valve stem and thereby open the passages 28 so that the volumetric spaces on opposite sides of the piston will be intercommunicated. With this arrangement, the valve heads and stem of the piston readily conditions the piston for axial shifting movement in the opposite direction without encountering the high pressure normally associated with piston and cylinder unites of the conventional double acting type. Further, the present piston and cylinder unit does not utilize a spring even though the unit is conditioned for the next cutting stroke by merely releasing the handle. Thus a user may readily cut or prune trees by depressing the handle which produces the cutting stroke and then immediately release the handle for return of the blade to the open position. The relief valve in the cylinder readily reduces the pressure which would tend to resist the piston when it is moved in the cutting direction.

From the foregoing description, it will be seen that I have provided a lightweight novel portable cutting device which is power operated by hydraulic system and wherein all of the components of the hydraulic system are carried on a mounting structure which may be comfortably strapped to a users back. Further, the use of a novel control valve which is mounted on one end of the handle of the cutting implement permits a user to shift the blade through the cutting stroke by merely depressing an operating lever, but which returns the blade to the open position by merely releasing the operating lever. The return of the blade to the open condition is 6 positively accomplished by hydraulic power rather than by the use of mechanical springs and the like.

The present portable cutting device also incorporates a relief valve in the piston of the hydraulic piston and cylinder unit so that the piston is readily conditioned for the forward or advance stroke when the operating lever is released.

Thus it will be seen that I have provided a novel portable cutting device which is not only of simple and inexpensive construction, but one which functions in a more efficient manner than any heretofore known comparable device.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the various parts without departing from the scope of my invention.

What I claim is:

l. A portable tree cutting device comprising an elongate handle,

a substantially flat mounting member secured to one end of said handle,

a substantially flat cutting member pivotally connected to said mounting member and being swingable into and out of engaging relation with respect to said mounting member between opened and closed positions, cylinder spaced from said handle and being pivotally connected with one of said members, a piston shiftable in said cylinder, a piston rod secured to said piston and extending exteriorly from said cylinder and being pivotally connected to the other of said members, said piston having a passage therethrough, a valve for closing said passage in the piston and being shiftable from a closed position to an open position during the terminal portion of travel of the piston in one direction, a pair of pressure conduits each being interconnected in communicating relation to said cylinder on opposite sides of said piston, supply conduit and a return conduit each being connected in communicating relation to a source of hydraulic fluid under pressure,

a control valve. mounted on the other end of said handle and including a housing having a supply passage therein intercommunicating said supply conduit with one of said pressure conduits, a return passage in said housing connected in communicating relation to said return conduit an outlet passage in said housing connected in communicating relation to said supply passage, an intermediate passage connected in communicating relation to said return passage, valve member mounted in said valve housing and being shiftable between first and second positions, said valve member having a passage therethrough in continuous communication with with said intermediate passage, and selectively communicating with said supply passage and said outlet passage, said valve member when in said first position being disposed in obstructing relation with said supply passage and preventing the flow of hydraulic fluid from said supply conduit through one of said pressure conduits, but permitting the flow of hydraulic flow through said outlet passage and through the other of said pressure conduits whereby the piston rod is retracted and the cutting member is in the open position, said valve passage communicating with said supply passage when said valve member is in said first position,

said valve member when in the second position being disposed in obstructing relation with said outlet passage but permitting the flow of hydraulic fluid through said supply passage from said supply conduit and through said one pressure conduit whereby the piston rod is extended and the cutting member is shifted to the closed position, said valve passage communicating said outlet passage with said intermediate passage when said valve member is in the second position,

yieldable means normally urging said valve member to said first position,

an operating lever connected to said valve member for shifting the same between said first and second positions.

2. The cutting device as defined in claim 1 wherein said valve for closing said piston port is comprised of a valve stem having a pair of valve heads affixed thereto, each of said valve heads being selectively disposed in closing relation with respect to said port.

3. The cutting device as defined in claim 1 and a support structure, a pump mounted on said support structure, power means for driving said pump and mounted on said support structure, a reservoir mounted on said support structure and adapted to contain a predetermined amount of hydraulic fluid, said supply conduit being connected with said pump and said return conduit being connected with said reservoir,

and attachment on said support structure engagable with a user to permit releasable attachment of the support structure on the back of a user. 

1. A portable tree cutting device comprising an elongate handle, a substantially flat mounting member secured to one end of said handle, a substantially flat cutting member pivotally connected to said mounting member and being swingable into and out of engaging relation with respect to said mounting member between opened and closed positions, a cylinder spaced from said handle and being pivotally connected with one of said members, a piston shiftable in said cylinder, a piston rod secured to said piston and extending exteriorly from said cylinder and being pivotally connected to the other of said members, said piston having a passage therethrough, a valve for closing said passage in the piston and being shiftable from a closed position to an open position during the terminal portion of travel of the piston in one Direction, a pair of pressure conduits each being interconnected in communicating relation to said cylinder on opposite sides of said piston, a supply conduit and a return conduit each being connected in communicating relation to a source of hydraulic fluid under pressure, a control valve mounted on the other end of said handle and including a housing having a supply passage therein intercommunicating said supply conduit with one of said pressure conduits, a return passage in said housing connected in communicating relation to said return conduit an outlet passage in said housing connected in communicating relation to said supply passage, an intermediate passage connected in communicating relation to said return passage, a valve member mounted in said valve housing and being shiftable between first and second positions, said valve member having a passage therethrough in continuous communication with with said intermediate passage, and selectively communicating with said supply passage and said outlet passage, said valve member when in said first position being disposed in obstructing relation with said supply passage and preventing the flow of hydraulic fluid from said supply conduit through one of said pressure conduits, but permitting the flow of hydraulic flow through said outlet passage and through the other of said pressure conduits whereby the piston rod is retracted and the cutting member is in the open position, said valve passage communicating with said supply passage when said valve member is in said first position, said valve member when in the second position being disposed in obstructing relation with said outlet passage but permitting the flow of hydraulic fluid through said supply passage from said supply conduit and through said one pressure conduit whereby the piston rod is extended and the cutting member is shifted to the closed position, said valve passage communicating said outlet passage with said intermediate passage when said valve member is in the second position, yieldable means normally urging said valve member to said first position, an operating lever connected to said valve member for shifting the same between said first and second positions.
 2. The cutting device as defined in claim 1 wherein said valve for closing said piston port is comprised of a valve stem having a pair of valve heads affixed thereto, each of said valve heads being selectively disposed in closing relation with respect to said port.
 3. The cutting device as defined in claim 1 and a support structure, a pump mounted on said support structure, power means for driving said pump and mounted on said support structure, a reservoir mounted on said support structure and adapted to contain a predetermined amount of hydraulic fluid, said supply conduit being connected with said pump and said return conduit being connected with said reservoir, and attachment on said support structure engagable with a user to permit releasable attachment of the support structure on the back of a user. 